These are almost always fan-made modifications. Some are simple texture packs that give the PC/Android version of SA a "Stories" look. Others are custom-made "total conversion" mods that create a new story within the San Andreas game engine.
If you have an active Netflix subscription, you can download the mobile remaster of GTA: San Andreas – The Definitive Edition for free on iOS and Android. It fixes many bugs from the original mobile port and looks beautiful. Gta San Andreas Stories Psp Download